1. Field of the Invention
This invention relates to a surgical instrument and, more particularly, to a surgical snare suitable for use in carrying out polypectomy procedures.
2. Description of the Prior Art
Surgical snares suitable for use in removing polyps, such as those which are found in the colon of surgical patients, have been in use for many years. Although such instruments have been used with some success, they have left a great deal to be desired. Surgical snares in general have comprised an elongated flexible sheath connected at its proximal end to an operating handle. Extending through the sheath is an elongated flexible cable, the proximal end portion of which is connected to a movable portion of the operating handle so that the cable can be retracted and protracted by the surgeon relative to the sheath. An operating loop is connected to the distal end portion of the cable which is opened and closed by the surgeon to the extent that he shifts the movable portion of the operating handle to protract or retract the cable. When the cable is in its protracted or forward position, the operating loop is outside the sheath and in its fully extended position. As the cable is retracted, the loop is drawn into the sheath and closed.
Previous surgical snares have generally suffered from common deficiencies such as ease of manipulation of the operating loop at the point of application, usually within the gastointestinal tract of a surgical patient. As can be appreciated, during periods of actual use, a surgical snare must be manipulated and operated with a high degree of precision and control. Additionally, due to the fact that a cauterizing and cutting electrical current is generally used, the surgical loop cannot touch portions of the body other than the one which is to be removed. In light of this, prior manufacturers have attempted to use a very thin wire as the operating loop. While the thin wire allows more convenient manipulation, it also presents a serious and potentially lethal problem in that frequently there is premature severing of the polyp. This can lead to internal bleeding and infection, neither of which is acceptable in modern surgical procedures. As a result of this, the operating loop was made using a resilient spiral sleeve through which a core member was extended. Thus, the width was great enough to effectively prevent unnecessary, premature removal of the polyp during strangulation and at the same time was small enough to allow a tolerable degree of manipulation. This recent development is shown and described in U.S. Pat. No. 3,828,790 (1974) to Curtiss et al which is relevant prior art.
In addition, existing snare handles for use with the available surgical snares are manufactured in a manner such that in order to rotate the operating loop, while trying to engage the polyp, it is necessary to rotate the entire handle in order to rotate the operating loop. The operating loop handle usually has an electrical wire connected to an RF generator. While rotating the entire handle, the wire has a tendency to become wrapped around the surgeon's hand and is in general an unwieldy method for rotating the snare. In light of this, a need has arisen for a surgical snare having an operating loop which is freely rotatable while the handle remains relatively stationary.
Other relevant prior art is Wallace, U.S. Pat. Nos. 2,484,059 (1949), 2,545,865 (1951) and 2,888,017 (1959); Scott et al, U.S. Pat. No. 2,448,741 (1948); Willinsky, U.S. Pat. No. 2,487,502 (1949); Zingale, U.S. Pat. No. 3,149,633 (1964); Wappler, U.S. Pat. No. 3,752,159 (1973); and Seuberth Pat. al, U.S. Patent No. 3,805,791 (1974).